Production of coke



$atenteci Sept. 22, 1931 PATENT OFFICE WALTER BROADBRIDGE, EDWIN ma, AND WARWICK STENHING,-

LONDON, ENGLAND, ASSIGNOBS TO MINERALS SEPARATION NORTH AMERICA! @1- PORA'I'ION, OF NEW YORK, H. Y., A CORPORATION 4 EDUCTION OF COKE No Drawing. Original application filed Eovember 20, 1922, Serial No. 602,251, and in Great Britain November 29, 1921. Divided and this application filed April 22, 1926. Serial No. 103,988.

This invention relates to the production of coke from coal, and is herein described as applied to the production of coke of relatively much lower ash than the lump raw coal used a as raw material.

In our previous United States Patent No. 1,504,861 we have described various processes of producing a glomerates from impure coal, coal dumps an the like adapted for the making of bri uettes. We have now found that particles 0 coal and the like can be flocculated under such conditions as to fa-cilitatethe separation of water therefrom without the roduction of briquettes under water-expel ing pressure.

We have found that various agents such as certain oils, tars and other hydrocarbons or carbonaceous liquids which are incapable of forming briquettes of the carbonized mate- 0 rials such as coal under the conditions hereinafter described have the properties- 1 Of coating the coal particles, and

t2 Of causing the coal particles, when so coated, to flocculate together.

We have further found that this flocculating efiect occurs with ve small quantities of the agents referred to w en the coal particles are agitated with the flocculating agent 7 in suiiicient water to make a mobile pulp preferably with aeration. The quantities o the reagents may be very small, (from 3 to 10% of the weight of the coal, for examplezl suflicient only to coat the coal particles wit a thinfilm of the agent like a varnish, and

as quite insufiicient to fill the interstitial spaces between the flocculated particles. The flocculates include in the interstitial spaces a large proportion of water, but owing to the fact that the surfaces of the particles have become repellant of the water, it is possible to remove contained water by filtration or draining, preferablfy assisted by pressure, and thus the drying o the particles becomes a simple matter.

The removal of the water associated with the coated and flocculated particles may be assisted by pressure, but it is to be understood that it is not an ob et of the present invention'to convert the msiterials into briquettes,

V and the coating and flocculating agent does not perform the function of a binding medium to form briquettes. I

The presence of the flocculating agent assists the coking of special types of coal which would otherwise be unsuitable for making coke. According to the present invention therefore a process for producing coke may consist in agitating a pulp of suitably powdered coal with a suitable flocculating agent under such conditions that the coal is flocculated and coated with a water-repellant coatingadapted to be partly volatilized in a. subsequent coking operation and having so little adhesiveness as not to cause the coal to form into hard briquettes under water-expelling pressure, se arating and draining the flocculated coal, and cokin the drained coal. The tarry residue from t e volatilized matter, or some part of this, may be utilized as the flocculating agent in treating further masses of carbonaceous material. 7

The quantity of the flocculating agent employed should be suflicient to produce the flocculation at the temperature of the circuit water. It may be reduced by using a heated circuit, but preferably the treatment is carried out at atmospheric temperature. From 3 to 5% has been found suflicient when using as agent a product such as anthracene oil, and coal-tar, coal-tar oil and other reagents may be employed in like proportion. The following examples illustratevarious procedures in accordance with the invention Example I Goal from a Durham. Colliery was ground to pass a screen of 0.4 mm. aperture. The ground coal was concentrated by flotation, using 0.23 kilos cresol and 0.06 kilos kerosene oil er ton-of coal. The concentrates removed ha a water-solid ratio of 1.3 1.

The concentrates with their associated water were placed in a vessel of square horizontal section and were agitated by an impeller rotating with a peripheral velocity of about 200 meters per minute. By-product coke-oven coal-tar was added during the agitation, the quantit of tar amounting to 4% of the weight of t e dry-concentrates. The 100 test was carried out at room temperature. The coal become intensely flocculated and readily separable from the water. Removal of the bulk of the water was effected by draining; it could be assisted if desired by subjecting the flocculated 'coal to compression. Under a pressure of 310 kilos per square cm. the coal became substantially free from water, so much so that on drying it in a water oven at a temperature of 100 C. for a period of 3 hours, the weight diminished by 2.7%, which indicates the reduction in water content.

The coal was thus formed into a cake-which, however, could be easily crumbled between the fingers. It will be understood that it is not essential to compress the coal into cakes in this way although this may be done both to assist removal of the water and to facilitate handling of the treated material.

A full oven charge (about 7 tons) of the above coal, flocculated as described above and pressed into soft ovoids at a pressure of about 310 kilos per sq. cm., was coked, the time of heating being about hours. The resulting coke was of excellent quality, specially suitable for metallurgical use; it showed no trace of ovoid structure, and sustained a pressure of 160 kilograms per sq. cm. without crushing. It was found that the oven capacity was increased by more than 12%.

Example ll Coal from Powell Dufiryn Collieries was ground to pass a screen with an aperture of 0.4 mm. The coal was concentrated by flotation using 0.3 kilos cresol and 0.23 kilos kerosene oil per ton of coal, in which operation the ash content was reduced from 15% to 5%.

The concentrates removed had a watersolid ratio of 1.33 :1.

The concentrates with their associated water were transferred to a Vessel in which they were agitated as in Example I, and during the agitation the coal-tar product known as anthracene oil was added, the quantity of oil amounting to 3% of the weight of the dry concentrates. This operation was carried out at room temperature. An intense flocculation was produced, and when some of the wet flocculated coal was placed on a screen having 24 apertures per lineal centimeter, clear water ran through, and the greater part of the contained water drained away.

When the wet flocculated coal was placed in a mould having slits for egress of water and subjected. to a pressure of 80 kilos per square 0mg, some further water exuded and a cake was formed which contained 12% water. I 1

A pressure of 160 kilos per square cm. produced a cake containing 9% of water. In either case the cake crumbled easily in the fingers.

The cake was crumbled, packed into a silica pot, and heated for two hours at a temperature rising gradually to 1040 C. Excellent coke suitable for metallurgical use was produced; it sustained a pressure of 160 kilograms per sq. cm. without crushing.

It is possible to e ect not only the flocculation of the coal particles and the removal of the water therefrom, but also, in the same operation, it is possible to effect the separation of the gangue and other ash-forming materials from the coal particles.

Thus, accordin to this form of the invention, the fine y divided coal particles, mixed with gangue or other ash-forming materials, are suspended in sufficient water to make a mobile pulp. This pulp is then subjected to agitation (preferably with aeration) with a fiocculating agent of the kind hereinbefore described in quantity insuflicient to form an amalgam in which the interstitial spaces between the particles would be filled with the agent but suflicient to coat the coal particles and flocculate them in water, the gangue particles not being so coated or flocculated, the gangue. with the water, being separated from the coal by draining or filtration, with or without pressure, but without the production of briquettes.

E wample l I I Waste coal or dufi' ground to ass a screen with 0.-i mm. aperture from the owell Duffryn Mine in South Wales and containing 23.04% of ash was made up into a mobile pulp with an equal weight of water, and the pulp was agitated with the addition of 4.75% of by-product coke-oven coal-tar measured on the weight of the crude coal so as to pro duce flocculation. The wet flocculated coal was then transferred to a press and subjected to a pressure of 310 kilos per square cm. thereby extruding the water which carried the great proportion of the gangue. The resulting cake contained only 13% of ash and 5.56% of moisture. This test was carried out at normal atmospheric temperature.

The cake was crumbled, packed into a silica pot, and heated for two hours at a temperature rising gradually to 1040 C. Excellent coke suitable for metallurgical use was produced; it sustained a pressure of 160 kilograms per sq. cm. without crushing.

Again the process of flocculating the coal particles may be carried out in such a way that the coal particles are coated and flocculated and separated in the form of a float supported by bubbles while the gangue remains in the water, thus obtaining a float relatively free from ash as compared with the raw coal.

Example IV The same material as in Example III, viz, ulverized waste coal or dufi' from the Powell V uifryn Mine in South Wales ground to pass a screen with 0.4 mm. aperture was mixedwith its own weight of Water to form a mobile pulp. There was added to this pulp the following reagents 4.7% by-product coke-oven coal-tar, 0.075% cresol, 0.075% kerosene oil, (these percentages being measured on the weight of crude coal).

After agitation and aeration the flocculated coal separated as a float supported by bubbles, and was removed and subjected to a pressure of 310 kilos per square cm. The resulting cake contained only 5.76% of ash and 3.87% of moisture.

The cake was crumbled, packed into a silica pot, and heated for two hours at a tempera? ture rising gradually to 1040 C. Excellent coke suitable for metallurgical use was produced; it sustained a pressure of 160 kilograms per sq. cm. Without crushing.

This test was carried out at normal temperature.

This application is a division of our copending application Serial Number 602,251,

filed November 20th, 1922-, upon which Patent No. 1,606,867 was issued November 16, 1926.

Having thus described certain embodiments of our invention, we claim 1. A process for producing coke which consists in agitating an aqueous pulp of finely divided coal with a flocculating agent having the characteristics of both a frothing agent and a coating oil, so that the coal is flocculated and coated with a water-repellant coating having so little adhesiveness as not to cause the coal to form into briquettes under water-expelling pressure, separating an draining the flocculated coal, and coking the drained coal. v

2. A process for producing coke which consists in agitating an aqueous pulp of finely divided coal with a flocculating agent containing both a water-soluble frothing agent and a coating oil, so that the coal is flocculated and coated with a water-repellant coating having so little adhesiveness as not to cause the coal to form into briquettes under water-expelling pressure, separating and draining the flocculated coal, and coking the drained coal.

3. A process -for producing coke which consists in agitating an aqueous pulp of finely divided coal with a few per cent. of a coal tar under such. conditions that the coal is flocculated and coated with a water-repellant coating having so little adhesiveness as not to cause the coal to form into briquettes under water-expelling pressure, separating and draining the fiocculated coal, and coking the drained coal.

4. A process for producing coke which consists in agitating an aqueous pulp of finely divided coal with about three per cent. of a flocculating agent, so that the coal is flocculated and coated with a water-repellant coating having so little adhesiveness as not to cause the coal to form into briquettes under water-expelling pressure, separating and draining the flocculated coal and coking the drained coal.

5. A rocess for producing coke which cons sts in agitating an aqueous pulp of finely divided coal with a flocculating agent, so that the coal is fiocculated and coated with a water-repellant coating having so little adhesiveness as not to cause the coal to form into briquettes under water-expelling pressure, separating the flocculated coal, drainmg it under a pressure of the order of magnitude of 160 kilograms to the square centimeter, and cokin the drained coal.

6. A rocess or producing coke which consists in agitating an aqueous pulp of finely divided coal with a few per cent. of a coal tar, so that the coal is fiocculated and coated with a water-repellant coating having so little adhesiveness as not to cause the coal to form into briquettes under water-expelling pressure, separating the flocculated coal,

draining it under a presssure of the order of magnitude of 160 kilograms to the square centimeter, and coking the drained coal.

7. A process for producing a low-ash coke which consistsgin agltating an aqueous pulp of finely divided coal with a flocculating agent so that the coal is fiocculated and coated with a water-repellant coating having so little adhesiveness as not to cause the coal to form into briquettes under water expelling pressure, separating the flocculated coal and draining it under water-expelling presd sure, whereby the coal is obtained relatively dry and of diminished ash content, and coking the drained coal.

8 A process for producing a low-ash coke which consists in agitating an aqueous pulp of finely divided carbonized coal with a few per cent. of a coal coating and flocculating coal tar product, .so that the coal is flocculated and coated with a water-repellant coating having so little adhesiveness as not to cause the coal to form into briquettes under water-expelling pressure, separating the flocculated coal and draining it under waterexpelling pressure, whereby the coal is obtained relatively dry and of diminished ash content, and coking the drained coal.

9. A process for producing a low-ash coke which consists in agitating an aqueous pulp of finely divided coal with a few per cent. of

coal to froth-flotation concentration with a frothing a ent to produce a. coalconcentrate of diminis ed ash content, agitatlng a mobile pulp of the concentrate with a few per cent.

of a flocculating agent so that the coal is flocculated and coated with a water-repellant coating having so little adhesiveness as not to cause the coal to form into briquettes under water-expellin pressure, separating and draining the floccu ated coal, and coking the drained coal.

11. A process for producing a low-ash coke which consists in subjecting finely divided coal to froth-flotation concentration with a frothing agent including a water soluble element to produce a coal concentrate of diminished ash content, agitating a mobile pul of the concentrate with a few per cent. 0 a occulating agent so that the coal is flocculated and coated with a water-repellent coating having so little adhesiveness as not to cause the coal to form into briquettes under waterexpelling pressure, separating and draining thelflocculated coal, and coking the drained coa 12. A process for producing a low-ash coke which consists in subjecting finely divided coal to froth-flotation concentration with a frothing agent containing a few per cent. of a coal tar to'produce a coal concentrate of diminished ash content, agitating a mobile pulp of the concentrate with a few per cent.

of a flocculating agent so that the coal is flocculated and coated with a waterrepellant coating having so little adhesiveness as not to cause the coal to form into briquettes under water-expelling pressure, separating and draining the flocculated coal, and coking the drained coal.

13. A process for producing a low-ash coke which consists in subjecting finely divided coal to froth-flotation concentration with a frothing agent containing a few per cent. of a coal tar and an oily substance, to produce a coalconcentrate of diminished ash content, agitating a mobile pulp of the concentrate with a few per cent. of a flocculating agent so that the coal is flocculated and coated with a water-repellant coating having so little adhesiveness asnot to cause the coal to'form into briquettes under water-expel: ling pressure, separating and draining the flocculated coal, and coking the drained coal. 14. A process for producing a low-ash coke which consists in-subjecting finely divided coal to froth-flotation concentration with a frothing agent, so that the coal is flocculated with diminished ash content and coated with a water-repellant coating having so little adhesiveness as not to cause the coal to form into briquettes under waterexpelling pressure, separating the flocculated coal an draining it under water-expelling pressure, and cokin the drained coal.

15. A process. or producing a low-ash and coated with a water-repellant coating 1 having so little adhesiveness as not to cause the coal to form into briquettes under waterexpelling pressure, separating the flocculated coal and draining it under water-expelling 1 pressure, and coking the drained coal.

16. A process for producing a low-ash coke which consists in subjecting finely divided coal to froth-flotation concentration with a few per cent. of a coal tar so that the coal is flocculated with diminished ash content and coated with a water-repellant coating having so little adhesiveness as not to cause the coal to form into briquettes under water-expelling pressure, separating the flocculated coal and draining it under waterexplelling pressure, and coking the drained coa 17. A process for producing a low-ash coke Which consists in subjecting coal to frothflotation concentration with a frothing agent containing a few per cent. of a coal tar so that the coal is flocculated with diminshed ash content and coated with a water -repellant coating having so little adhesiveness as not to cause the coal to form into briquettes under water-expelling pressure, separating the flocculated coal and draining it under a pressure of the order of magnitude of 160 kilograms to the square centimeter, and coking the drained coal.

18. A process for producing a low-ash coke which consists in subjecting coal to frothflotation concentration with a frothing agent containing a few per cent. of a coal coating and flocculating coal tar product, so that the coal is flocculated with diminished ash content and coated with a water-repellant coating having so little adhesiveness as not to cause the coal to form into briquettes under water-expelling pressure, separating the flocculated coal and draining it under a pressure of the order of magnitude of 160 kilograms to the square centimeter, and coking the drained coal.

19. A process for producing coke which consists in agitating an aqueous pulp of powdered coal with a flocculating agent so that the coal is flocculated and coated with a water-repellant coating adapted to be partly volatilized in a subsequent. coking operation and having so little adhesiveness as not to cause the coal to form into briquettes under water-expelling pressure, separating and draining the flocculated coal, andcoking the drained coal. j

20. A process for producing coke which consists in agitating an aqueous pulp of powdered coal with a flocculating agent so that the coal is flocculated and coated with a wa- ISO ter-repellant coating adapted to be partly volatilized in a subsequent coking operation and having so litle adhesiveness as not to cause the coal to form into briquettes under water-expelling pressure, separating and draining the flocculated coal, coking the drained coal, and recovering volatilized flocculating agent. 21. A process for producing coke which consists in agitating an aqueous pulp of powdered coal with a coal tar so that the coal is flocculated and coated with a water-repellant coating adapted to be partly volatilized in a subsequent coking operation and having so 35 little adhesiveness as not to cause the coal to form into briquettes under water-expelling pressure, separating and draining the flocculated coal and coking the drained coal.

22. A process of producing coke which 29 consists in agitating an aqueous pulp of powdered coal with a few per cent. of a flocculating agent so that the coal is fiocculated and coated with a water-repellant coating adapted to be partly volatilized in a subsequent coking operation and having so little adhesiveness as not to cause the coal to form into briquettes under water-expelling pressure, separating and draining the fiocculated coal,

and coking the drained coal.

39 23. A process for producing a low-ash coke which consists in subjecting an aqueous pulp of powdered coal to froth-flotation concentration to form a concentrate of diminished ash content, agitating a mobile pulp of the concentrate with a flocculating agent so that the coal is flocculated and coated with a Water-repellant coating adapted to be partly volatilized in a subsequent coking operation and having so little adhesiveness as not to 40 cause the coal to form into briquettes under water-expelling pressure, separating and draining the flocculated coal, and coking the drained coal.

In testimony whereof we aflix our signatures.

WALTER BROADBRIDGE. ED EDSER.

WARWICK STENNING. 

